Surgical instrumentation and method for treatment of the spine

ABSTRACT

Instrumentation for treatment of the spine, including an elongate member having a deformable distal end portion at least partially formed of a flexible and preferably elastic material. The distal end portion has an initial configuration for placement adjacent a vertebral body and a deformed configuration defining at least one outwardly extending projection for displacement of at least a portion of the vertebral body. The elongate member preferably comprises a rod member, a sleeve member and an actuator mechanism for imparting relative linear displacement between the rod and sleeve members to effect outward deformation of the distal end portion of the sleeve member. In one embodiment, the instrumentation is used to compact cancellous bone to form a cavity within a vertebral body. In another embodiment, the instrumentation is used to reduce a compression fracture. In yet another embodiment, the instrumentation is used to distract a disc space between adjacent vertebral bodies.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of Provisional ApplicationSer. No. 60/224,491, filed Aug.11, 2000 and entitled Vertebral PlastyReduction Device, the contents of which are hereby incorporated byreference in their entirety.

FIELD OF THE INVENTION

The present invention relates generally to the field of surgicalinstrumentation and methods for treatment of the spine, and moreparticularly relates to instrumentation and methods for transverselydisplacing structures associated with the spine.

BACKGROUND OF THE INVENTION

Various instruments and methods for the treatment of compression-typebone fractures and other osteoporotic and/or non-osteoporotic conditionshave been developed. Such methods generally include a series of stepsperformed by a surgeon to correct and stabilize the compressionfracture. A cavity is typically formed in the bone to be treated,followed by the insertion of an inflatable balloon-like device into thebone cavity. Inflation of the balloon-like device causes a compaction ofthe cancellous bone and/or bone marrow against the inner cortical wallof the bone, thereby resulting in enlargement of the bone cavity and/orreduction of the compression fracture. The balloon-like device is thendeflated and removed from the bone cavity. A biocompatible fillingmaterial, such as methylmethacrylate cement or a synthetic bonesubstitute, is sometimes delivered into the bone cavity and allowed toset to a hardened condition to provide internal structural support tothe bone.

While the above-described instruments and methods provide an adequateprotocol for the treatment and fixation of compression-type bonefractures, it has been found that expansion of the balloon-like deviceis not controllable. Instead, when such balloon-like device is inflated,expansion occurs along a path of least resistance. As a result, thedirection of compaction of the cancellous bone and/or reduction of thecompression fracture is not controllable, and expansion occurs inmultiple directions and along multiple axes.

Thus, there is a general need in the industry to provide surgicalinstrumentation and methods for use in treatment of the spine thatprovide a greater degree of control over transverse displacement ofstructures associated with the spine than is currently available withinthe industry. The present invention meets this need and provides otherbenefits and advantages in a novel and unobvious manner.

SUMMARY OF THE INVENTION

The present invention relates generally surgical instrumentation andmethods for displacement of at least a portion of a vertebral body.While the actual nature of the invention covered herein can only bedetermined with reference to the claims appended hereto, certain formsof the invention that are characteristic of the preferred embodimentsdisclosed herein are described briefly as follows.

In one form of the present invention, instrumentation is provided fortreatment of the spine, comprising an elongate member extending along alongitudinal axis and including a deformable distal end portion havingan initial configuration for placement adjacent a spinal structure and adeformed configuration defining at least one transverse projection fortransverse displacement of at least a portion of the spinal structure.

In another form of the present invention, instrumentation is providedfor treatment of the spine, comprising a first member, a second memberhaving a distal end portion engaged with the first member, with thedistal end portion having an initial configuration for placementadjacent a spinal structure and an expanded configuration fordisplacement of at least a portion of the spinal structure, and whereinrelative displacement between the first and second members causes thedistal end portion to reform from the initial configuration toward theexpanded configuration.

In yet another form of the present invention, instrumentation isprovided for treatment of the spine, comprising a member including adeformable distal end portion having an initial configuration forpositioning adjacent a spinal structure and a deformed configuration fordisplacing at least a portion of the spinal structure, and means formechanically deforming the distal end portion from the initialconfiguration toward the deformed configuration to displace the spinalstructure in at least one predetermined direction.

In still another form of the present invention, a method is provided fortreatment of the spine, comprising providing an instrument including adistal end portion having an insertion configuration and a deformedconfiguration. The method further comprises positioning the distal endportion adjacent a spinal structure while in the insertion configurationand deforming the distal end portion toward the deformed configurationto displace at least a portion of the spinal structure.

It is one object of the present invention to provide improved surgicalinstrumentation and methods for treatment of the spine.

Further objects, features, advantages, benefits, and aspects of thepresent invention will become apparent from the drawings and descriptioncontained herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a surgical instrument according to oneform of the present invention.

FIG. 2 is an exploded side view of a distal end portion of the surgicalinstrument depicted in FIG. 1.

FIG. 3 is an exploded side view of a proximal end portion of thesurgical instrument depicted in FIG. 1.

FIG. 4 is a broken cross-sectional side view of the surgical instrumentdepicted in FIG. 1.

FIG. 5 is a perspective view of the distal end portion of the surgicalinstrument depicted in FIG. 1, as shown in an initial configuration.

FIG. 6 is a perspective view of the distal end portion depicted in FIG.5, as shown in a deformed configuration.

FIG. 7 is a perspective view of the distal end portion of a surgicalinstrument according to another form of the present invention, as shownin an initial configuration.

FIG. 8 is a perspective view of the distal end portion depicted in FIG.7, as shown in a deformed configuration.

FIG. 9 is a perspective view of the distal end portion of a surgicalinstrument according to another form of the present invention, as shownin an initial collapsed configuration.

FIG. 10 is a perspective view of the distal end portion depicted in FIG.9, as shown in a partially expanded configuration.

FIG. 11 is a perspective view of the distal end portion depicted in FIG.9, as shown in a fully expanded configuration.

FIG. 12 is a partial cross-sectional side view of a spinal columnillustrating treatment of a vertebral body using the surgical instrumentillustrated in FIG. 1.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is hereby intended, such alterations and further modificationsin the illustrated devices, and such further applications of theprinciples of the invention as illustrated herein being contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

Referring to FIG. 1, shown therein is an instrument 20 for treatment ofthe spine according to one form of the present invention. Instrument 20is particularly useful for placement adjacent a spinal structure andselective displacement of at least a portion of the spinal structure. Inone embodiment of the invention, the spinal structure is a vertebralbody. It should be understood that instrument 20 may be used inintrabody applications such as, for example, a vertebral plastyprocedure to compact cancellous bone within the vertebral body and/or toreduce a compression fracture of the vertebral body. Additionally, itshould be understood that instrument 20 may be used in interbodyapplications such as, for example, to distract a space between adjacentvertebral bodies, such as the vertebral disc space. It should further beunderstood that in other embodiments of the invention, the spinalstructure may be comprised of a spinal implant such as, for example, acage device, or any other structure used in association with treatmentof the spine. Additionally, although instrument 20 is illustrated anddescribed in the context of treatment of a human spine, it should beunderstood that instrument 20 may be used to treat other animals. Itshould further be understood that instrument 20 may be used inassociation with applications outside of the spinal field such as, forexample, to treat other types of bony structures.

Instrument 20 is generally comprised of an elongate member 22 extendinggenerally along a longitudinal axis L and having a distal end portion 22a and a proximal end portion 22 b. Although the illustrated embodimentdepicts elongate member 22 as having a generally linear, unitaryconfiguration, it should be understood that elongate member 22 may takeon other configurations as well, such as, for example, a curvilinearconfiguration or a hinged configuration. Instrument 20 also includes anactuator mechanism 24 coupled to the proximal end portion 22 b ofelongate member 22. As will be discussed in greater detail below, thedistal end portion 22 a is deformable and is configured to outwardlyexpand in response to a mechanically induced force. Such force may beeffected, for example, by the selective actuation of actuator mechanism24.

As shown in FIGS. 5 and 6, the distal end portion 22 a is reformablebetween an initial configuration (FIG. 5) and a deformed configuration(FIG. 6). As used herein, the term “initial configuration” is broadlydefined to encompass a structural configuration of elongate member 22that is suitable for placement adjacent a spinal structure, and the term“deformed configuration” is broadly defined to encompass a structuralconfiguration of elongate member 22 that is suitable for displacement ofat least a portion of the spinal structure. As discussed above, in oneembodiment of the invention, the spinal structure is a vertebral body,and displacement of the vertebral body could be associated with eitherintrabody or interbody applications.

Referring to FIG. 2, shown therein are further details regarding theelongate member 22, and more specifically the deformable distal endportion 22 a of elongate member 22. In one embodiment of the invention,the elongate member 22 is comprised of an inner rod member 30 and anouter sleeve member 32. The inner rod 30 is preferably formed of asubstantially rigid medical grade material such as, for example,titanium or stainless steel. The distal end portion 30 a of rod 30includes a tapered portion 34, a reduced cross-section intermediateportion 36, and a rounded distal end portion 38. In one embodiment, theintermediate portion 36 has a diameter somewhat smaller than thediameter of the tapered portion 34 and the rounded distal end portion 38so as to define a pair of opposing shoulders 40, 42. Although rod 30 hasbeen illustrated and described as having a substantially circular crosssection, it should be understood that other shapes and configurationsare also contemplated as being within the scope of the inventionincluding, for example, elliptical, square, rectangular or otherpolygonal configurations.

The outer sleeve 32 preferably has a tubular configuration defining aninner passage extending therethrough generally along longitudinal axis Land sized to slidably receive rod 30. Sleeve 32 is preferably formed ofa flexible material that is capable of facilitating deformation from aninitial configuration toward a deformed configuration. Additionally,sleeve 32 is preferably formed of an elastic material that is capable offacilitating elastic deformation from the initial configuration towardthe deformed configuration and reformation back toward the initialconfiguration. Sleeve 32 may be formed of materials including, but notlimited to, titanium, stainless steel, an elastomer, a polymer, arubber, a composite material or a shape-memory material. Although theentire length of sleeve 32 may be formed of a flexible, elasticmaterial, it should be understood that only the distal end portion 32 aof sleeve 32 need be formed of such material, with the remainder ofsleeve 32 being formed of any suitable medical grade material. Moreover,although outer sleeve 32 is illustrated as having a substantiallytubular configuration, it should be understood that other shapes andconfigurations of sleeve 32 are also contemplated as being within thescope of the present invention. Additionally, although sleeve 32 hasbeen illustrated and described as being formed as a single-piece,unitary structure, it should be understood that the distal end portion32 a could be formed separately from the remainder of sleeve 32, andcoupled together by any known method, such as, for example, byfastening, welding or adhesion.

The distal end portion 32 a of sleeve 32 includes at least one slot 50extending generally along longitudinal axis L, and preferably includesat least a pair of slots 50 and 52 (not shown) disposed generallyopposite one another so as to define a pair of longitudinally extendingflexible strips of material 54, 56. It should be understood, however,that the distal end portion 32 a of sleeve 32 could be configured todefine any number of longitudinally extending slots, including three ormore slots, which would in turn define a corresponding number oflongitudinally extending flexible strips of material. It should furtherbe understood that distal end portion 32 a may include a number of slotsdisposed at various axial locations along longitudinal axis L. As willbe described below, the slots 50, 52 are provided to facilitate outwardbuckling of the distal end portion 32 a of sleeve 32 in at least onepredetermined direction upon the selective actuation of the actuatormechanism 24.

In the illustrated embodiment, the slots 50, 52 are substantiallyidentical in shape and configuration, and thus only slot 50 will bedescribed in detail. However, it should be understood that slots 50, 52may take on different shapes and configurations. Slots 50, 52 and stripsof material 54, 56 are illustrated as having a predetermined shape toprovide a degree of control over the outward buckling of the strips ofmaterial 54, 56. In one embodiment of the invention, the slots 50, 52and strips of material 54, 56 have an irregular shape. Slot 50 includesa relatively narrow and straight slot portion 60, a firsthourglass-shaped slot portion 62 formed by a first series of arcuateportions, and a second hourglass-shaped slot portion 64 formed by asecond series of arcuate portions. As will become apparent below, thewidened areas of the hourglass-shaped portions 62 and 64 serve asbending or flexion points to control the outward deformation of theflexible strips of material 54, 56.

The straight slot portion 60 extends longitudinally from the distal endof sleeve 32. The first hourglass-shaped portion 62 extendslongitudinally from slot portion 60 and includes a first widened area 62a, a narrowed area 62 b, and a second widened area 62 c. The secondhourglass-shaped portion 64 extends longitudinally from the firsthourglass-shaped portion 62 and includes a first widened area 64 a, anarrow area 64 b, and a second widened area 64 c. Although a specificconfiguration of slots 50, 52 have been illustrated and described, itshould be understood that other shapes and configuration of slots 50, 52are also contemplated as falling within the scope of the invention.

In one embodiment of the invention, the distal end portion 32 a ofsleeve 32 is secured to the inner rod 30 by way of a compression ring70. Specifically, the distal-most portion of sleeve 32 is disposed aboutportion 36 of rod 30, with the distal end of sleeve 32 abutting theshoulder 42 formed by the rounded distal end portion 38. The compressionring 70 is positioned about the distal-most portion of sleeve 32 and iscompressed thereabout, such as, for example, by mechanical crimping tosecure sleeve 32 to inner rod 30. As should be appreciated, slot portion60 aids in tightly compressing sleeve 32 about inner rod 30 to providesecure engagement therebetween. It should be understood that compressionring 70 could alternatively be compressed about distal-most portion ofsleeve 32 by other means, such as, for example, by forming compressionring 70 out of a shape-memory material that is reformable to a memorizedconfiguration having an internal diameter that is less than the outerdiameter of sleeve 32. It should further be understood that thedistal-most end portion of sleeve 32 could be secured to rod 30 by othermeans, such as, for example, by fastening, welding, adhesion or othermethods of attachment known to those of skill in the art.

Referring to FIGS. 3 and 4, shown therein are further details regardingthe actuator mechanism 24. Actuator mechanism 24 is generally comprisedof a rotary handle 100, a stationary handle 102, a connector assembly104, and an actuator member 106. As will be discussed in further detailbelow, the connector assembly 104 is configured to secure the elongatemember 22, and more specifically the outer sleeve 32, to the remainderof the actuator mechanism 24. As will also be discussed below, thethreaded actuator member 106 is coupled to the inner.rod 30 and isengaged with the rotary handle 100 such that rotational displacement ofhandle 100 about longitudinal axis L linearly displaces the actuatormember 106 along longitudinal axis L. As described above, the lineardisplacement of rod 30 relative to sleeve 32 causes the distal endportion 32 a of sleeve 32 to reform from its initial configurationtoward its deformed configuration.

The rotary handle 100 includes a pair of lateral extensions 110, 112extending outwardly from a main body portion 114 to define a T-handlearrangement which aids the surgeon in rotating the handle 100 relativeto the stationary handle 102. The main body portion 114 includes anopening extending along longitudinal axis L and having a threadedportion 116 and an unthreaded portion 118. A hub portion 120 extendsfrom the main body portion 114 and defines an annular groove 122.

The stationary handle 102 includes a pair lateral extensions 130, 132extending outwardly from a main body portion 134 to define a secondT-handle arrangement which aids the surgeon in securely grippinginstrument 20 and in maintaining the handle 102 in a stationaryrotational position during rotation of handle 100. The main body portion134 includes an opening extending therethrough along longitudinal axis Land defining a first cavity 136 and a second cavity 138. A pair ofopenings 140, 142 extend through the main body portion 134 and aredisposed in communication with the first cavity 136. The hub portion 120of handle 100 is inserted within the first cavity 136 and a pin orfastener 148 is inserted through opening 140 and positioned within theannular groove 122 to axially couple rotary handle 100 to stationaryhandle 102 while permitting relative rotational displacementtherebetween.

The actuator member 106 includes a threaded shank portion 150 and anunthreaded shank portion 152. The threaded shank portion 150 isconfigured to threadingly engage the threaded opening 116 in rotaryhandle 100. In one embodiment of the invention, the threaded shankportion 150 and the threaded opening 116 each define right hand threads.The unthreaded shank portion 152 includes a slotted opening 154extending therethrough that is aligned with the opening 142 in thestationary handle 102. A pin or fastener 155 is inserted through theopening 142 and the slotted opening 154 to couple the actuator member106 to the stationary handle 102. As should be apparent, pin 155substantially prevents relative rotational displacement between actuatormember 106 and handle 102 while allowing a limited amount of relativelinear displacement along longitudinal axis L. The distal end portion ofthe actuator member 106 includes a socket 156 configured to accept acorresponding ball portion 158 extending from the proximal end portion30 b of rod 30. The socket opening 156 includes a spherical portion 160sized to receive the ball portion 158 therein, and a cylindrical portion162 sized to receive the distal end portion 30 b of rod 30 therethroughto connect rod 30 to actuator member 106. It should be understood,however, that other methods of interconnecting rod 30 and actuatormember 106 are also contemplated as would occur to one of skill in theart.

As discussed above, the connector assembly 104 is configured to connectthe elongate member 22, and more specifically the outer sleeve 32, tothe remainder of the actuator mechanism 24. The connector assembly 104is generally comprised of a gripper member 170, a lock collar member 172and a biasing member 174. The gripper member 170 includes a connectingsegment 176, a gripping segment 178 and a longitudinal passage having afirst portion 180 extending through connecting segment 176 and a secondportion 181 extending through the gripping segment 178. The firstportion 180 of the passage is sized to receive the shank portion 152 ofactuator member 150 therein, and the second portion 181 of the passageis sized to receive the proximal end portion 32 b of sleeve 32 therein.

The gripping segment 178 of gripper member 170 has a generally conicalshape and includes a tapered outer surface 182. The gripping segment 178also includes a longitudinally extending slit 183 and a pair oftransverse slots 184 that intersect slit 183, with both the slit 183 andthe slots 184 intersecting the longitudinal passage 181. One purpose ofthe slit 183 and the slots 184 is to facilitate compression of thegripping segment 178 about the proximal end portion 32 b of sleeve 32.The proximal end portion 32 b of sleeve 32 defines an opening or window185 extending therethrough to further facilitate gripping of sleeve 32by gripping segment 178. Another purpose of slit 183 is to provide apassageway for the lateral insertion of the proximal end portion 30 b ofrod 30 therethrough to permit assembly with the actuator member 106. Thegripping segment 178 also includes an outer tapered surface 186, thepurpose of which will become evident below.

The connecting segment 176 of gripper member 170 defines an elongateopening 187 extending transversely therethrough and being positioned incommunication with the longitudinal slit 183. One purpose of theelongate opening 187 is to facilitate compression of the grippingsegment 178 about the proximal end portion 32 b of sleeve 32. Anotherpurpose of the transverse slot 187 is to provide a passageway for thelateral insertion of the ball portion 158 of rod 30 therethrough andinto engagement with the socket 156 defined in actuator member 106. Theconnecting segment 176 also includes an opening 188 extendingtransversely therethrough and aligned with the opening 142 in thestationary handle 102. Pin 155 is inserted through the opening 188 toaxially couple the gripper member 170, and in turn the elongate member22, to the stationary handle 102 in a manner that substantially preventsrelative linear and rotational displacement therebetween.

The lock collar member 172 includes a cylindrically-shaped body portion190, a tapered end portion 192, and a longitudinal passage 194 extendingtherethrough and being sized to receive the connecting segment 176 ofgripper member 170 therein. The cylindrical body portion 190 is sized tobe received within cavity 138 of stationary handle 102. The longitudinalpassage 194 includes an inner tapered surface 196 that corresponds tothe outer tapered surface 186 of gripping segment 178. In one embodimentof the invention, the biasing member 174 is a coil spring. However, itshould be understood that other types of biasing devices mayalternatively be used as would occur to one of skill in the art.

Referring to FIG. 4, spring 174 is disposed within the cavity 138 ofstationary handle 102 and is engaged against the proximal end of thelock collar 172 to bias the lock collar 172 toward the gripping segment178. The biasing of lock collar 172 engages the tapered inner surface196 tightly against the tapered outer surface 186 of gripping segment178. Such engagement creates an inward compression force onto thegripping segment 178 which causes the gripping segment 178 to collapsetightly about the proximal end portion 32 b of sleeve 32 to securelygrip sleeve 32 within the longitudinal passage 181. The tapered outersurface 192 of lock collar 172 is oriented at about the same angle asthe tapered outer surface 182 of gripping segment 178 to provide arelatively smooth transition between lock collar 172 and grippingsegment 178.

Based on the above description and corresponding illustrations, itshould be apparent that rotation of handle 100 relative to stationaryhandle 102 in a clockwise direction (assuming right hand threading) willcause the actuator member 106 to be linearly displaced in the directionof arrow A, which will correspondingly cause rod 30 to be linearlydisplaced in the direction of arrow A. Furthermore, since the distal endportion of sleeve 32 is engaged with the distal end portion of rod 30,linear displacement of rod 30 in the direction of arrow A will cause thedeformable distal end portion 32 a of sleeve 32 to buckle outwardlytoward the deformed configuration illustrated in FIG. 6. It should alsobe apparent that rotation of handle 100 relative to stationary handle102 in a counter-clockwise direction will cause the actuator member 106to be linearly displaced in the direction of arrow B, which willcorrespondingly cause rod 30 to be linearly displaced in the directionof arrow B. Linear displacement of rod 30 in the direction of arrow Bwill cause the deformable distal end portion 32 a of sleeve 32 to reformback toward the insertion configuration illustrated in FIG. 5. As shouldbe apparent, instead of rotating handle 100 relative to handle 102 toimpart relative linear displacement between rod 30 and sleeve 32, it isalso possible to hold handle 100 in a stationary position and to rotatehandle 102 relative to handle 100 to impart relative linear displacementbetween rod 30 and sleeve 32.

Although one specific embodiment of the actuator mechanism 24 has beenillustrated and described herein, it should be understood that the useof other types and configurations of actuator mechanisms are alsocontemplated as would occur to one of skill in the art. As should beapparent, any type of actuator mechanism that is capable of impartingrelative displacement between rod 30 and sleeve 32 to reform the distalend portion 32 a of sleeve 32 between the initial and deformedconfigurations may be used. It should further be understood that in analternative form of the invention, rod 30 may be manually displaced bythe surgeon relative to sleeve 32, thereby eliminating the need for aseparate actuator mechanism 24.

Referring now to FIGS. 5 and 6, shown therein is the distal end portion22 a of elongate member 22, as shown in an initial insertionconfiguration and a mechanically deformed expanded configuration,respectively. When in the initial configuration (FIG. 5), the distal endportion 32 a of sleeve 32 has a relatively low profile to facilitatepositioning adjacent a vertebral body. As should be appreciated, therounded distal end portion 38 reduces the likelihood of damage toadjacent tissue during such positioning. As used herein, positioning ofthe distal end portion 32 a adjacent a vertebral body is meant toinclude positioning of the distal end portion 32 a in proximity to avertebral body, within a vertebral body or within a space betweenadjacent vertebral bodies. As discussed above, instrument 20 may also beused in association with spinal structures other than a vertebral body,such as, for example, a spinal implant, with the distal end portion 32 aof sleeve 32 being positioned adjacent or within the spinal implant whenin the insertion configuration.

Once properly positioned adjacent the vertebral body, the distal endportion 32 a of sleeve 32 is mechanically deformed by displacing the rod30 relative to the sleeve 32. In the illustrated embodiment of theinvention, such relative displacement is accomplished by linearlydisplacing rod 30 relative to sleeve 32 in the direction of arrow A, andis initiated by the selective actuation of actuator mechanism 24. In analternative embodiment of the invention, the distal end portion 32 a ofsleeve 32 may be mechanically deformed toward the expanded configurationby way of relative rotational displacement between rod 30 and sleeve 32.

When reformed toward the expanded configuration (FIG. 6), the distal endportion 32 a of sleeve 32 is outwardly deformed relative to longitudinalaxis L so as to form a number of laterally extending projections orprotrusions 198 a, 198 b. As discussed above, the deformed configurationof instrument 20 may define any number of laterally extendingprojections, including a single projection or three or more projections,and may define a number of laterally extending projections at variousaxial locations along longitudinal axis L. It should be apparent thatthe number, position, and direction of the laterally extendingprojections is at least partially controlled by the configuration andplacement of the slots 50 in sleeve 32. In this manner, formation of thelaterally extending projections and the resulting displacement of thevertebral body is said to be directionally controlled. Moreover, if thedeformed configuration of instrument 20 defines a single projection 198a, or a single pair of opposing projections 198 a, 198 b aligned along acommon transverse axis T, then formation of the laterally extendingprojection and the resulting displacement of the vertebral body is saidto be uniaxial. Further, if the deformed configuration of instrument 20defines a single projection 198 a extending in a single direction, thenformation of the laterally extending projection and the resultingdisplacement of the vertebral body is said to be unidirectional.

Following displacement of the vertebral body, the distal end portion 32a of sleeve 32 may be reformed from its deformed/expanded configurationback toward its initial insertion configuration by linearly displacingrod 30 relative to sleeve 32 in the direction of arrow B. As discussedabove, the distal end portion 32 a of sleeve 32 may be formed of ashape-memory material, such as, for example, a shape-memory alloy(“SMA”) to aid in reforming the distal end portion 32 a from thedeformed configuration back toward its initial configuration. Morespecifically, SMAs are known to exhibit a characteristic or behavior inwhich a particular component formed of an SMA is capable of beingdeformed from an initial “memorized” shape or configuration to adifferent shape or configuration, and then reformed back toward itsinitial shape or configuration.

The ability to possess a shape-memory characteristic or behavior is aresult of the fact that the SMA undergoes a reversible transformationfrom an austenitic state to a martensitic state. If the martensitictransformation occurs due to the imposition of stress, the shape-memoryphenomena is referred to as stress-induced martensitic transformation.As a result, SMAs are known to display a superelastic or rubber-likebehavior in which a strain attained beyond the elastic limit of the SMAmaterial during loading is recovered during unloading. This superelasticphenomena occurs when stress is applied to an SMA article at atemperature slightly higher than the temperature at which the SMA beginsto transform into austenite (sometimes referred to as the transformationtemperature or A_(s)). When stressed, the article first deformselastically up to the yield point of the SMA material (sometimesreferred to as the critical stress). However, upon the furtherimposition of stress, the SMA material begins to transform intostress-induced martensite. This transformation takes place at anessentially constant stress, up to the point where the SMA material iscompletely transformed into martensite. When the stress is removed, theSMA material will revert back into austenite and the article willautomatically return toward its original, pre-programmed or memorizedshape without a corresponding change in temperature.

Further details regarding the superelastic phenomena of a SMA andadditional characteristics of stress-induced martensite are more fullydescribed by Yuichi Suzuki in an article entitled Shape Memory Effectand Super-Elasticity in Ni—Ti Alloys, Titanium and Zirconium, Vol. 30,No. 4, Oct. 1982, the contents of which are hereby incorporated byreference. Additionally, while there are many alloys that exhibitshape-memory or superelastic characteristics, one of the more commonSMAs is an alloy of nickel and titanium. One such well-known SMA isNitinol®, which has proven to be highly effective for devices to beplaced within the human body because its transformation temperaturerange generally falls between room temperature and normal human bodytemperature (i.e., at about 35-40 degrees Celsius). Moreover, Nitinol®has a very low corrosion rate and excellent wear resistance, therebyproviding an advantage when used as a support structure within the humanbody. Additionally, implant studies in animals have shown minimalelevations of nickel in the tissues in contact with the Nitinol®material. It should be understood, however, that other SMA materialsthat exhibit superelastic characteristics are contemplated as beingwithin the scope of the invention.

If the distal end portion 32 b of outer sleeve 32 is formed of an SMAmaterial and is reshaped or deformed while at a temperature above thetransformation temperature A_(s) of the SMA, the distal end portion 32 bwill automatically recover or reform toward its initial shape orconfiguration when the stress is removed from distal end portion 32 b.As illustrated in FIG. 5, when distal end portion 32 b is in itsunstressed initial configuration, virtually all of the SMA material willbe in an austenitic state. However, upon the imposition of stress ontodistal end portion 32 b (e.g., by turning actuator handle 100 in aclockwise direction relative to stationary handle 102), at least aportion of the SMA material will transform into reversiblestress-induced martensite as the distal end portion 32 b is deformedtoward the expanded configuration. Upon the reduction or removal of thestress (e.g., by turning actuator handle 100 in a counter clockwisedirection), at least a portion of the SMA material will be transformedback into austenite and the distal end portion 32 b will automaticallyreform back toward the initial configuration.

Referring now to FIGS. 7 and 8, shown therein is the distal end portionof an instrument 200 according to another form of the present invention,as shown in an initial insertion configuration and a mechanicallydeformed configuration, respectively. It should be understood thatinstrument 200 may be used in association with applications similar tothose discussed above with regard to instrument 20, including bothintrabody and interbody applications involving displacement of at leasta portion of a vertebral body.

Instrument 200 is generally comprised of an elongate member 222extending along a longitudinal axis L and having a distal end portion(as shown) and a proximal end portion (not shown) coupled to an actuatormechanism which may be configured similar to actuator mechanism 24. Thedistal end portion of elongate member 222 is deformable and isconfigured to outwardly expand in response to a mechanically inducedforce. Specifically, the distal end portion is reformable between aninitial configuration (FIG. 7) for positioning adjacent a vertebralbody, and a deformed configuration (FIG. 8) for displacement of at leasta portion of the vertebral body. Although the illustrated embodimentdepicts elongate member 222 as having a generally linear, unitaryconfiguration, it should be understood that elongate member 222 may takeon other configurations as well, such as, for example, a curvilinearconfiguration or a hinged configuration.

In the illustrated embodiment of instrument 200, the elongate member 222is generally comprised of an inner rod member 230 and an outer sleevemember 232. The inner rod 230 is preferably formed of a substantiallyrigid medical grade material such as, for example, titanium or stainlesssteel. The rod 230 includes a distal end portion 230 a that is disposedwithin and coupled to a distal end portion 232 a of sleeve 232. Althoughrod 230 has been illustrated and described as having a substantiallycircular cross, it should be understood that other shapes andconfigurations are also contemplated as being within the scope of thepresent invention, such as, for example, elliptical, square, rectangularor other polygonal configurations.

The outer sleeve 232 preferably has a tubular configuration defining aninner passage extending therethrough generally along longitudinal axis Land sized to slidably receive rod 230 therein. Sleeve 232 is formed of arelatively flexible material that is capable of being reformed from aninitial configuration to an expanded configuration. Preferably, sleeve232 is formed of a relatively elastic material that is capable of beingelastically deformed to the expanded configuration and reformed backtoward the initial configuration. Sleeve 232 may be formed of materialsincluding, but not limited to, titanium, stainless steel, an elastomer,a polymer, a rubber, a composite material or a shape-memory material.Although the entire length of sleeve 232 may be formed of a flexible,elastic material, it should be understood that only the distal endportion 232 a need be formed of such material, with the remainder ofsleeve 232 being formed of any suitable medical grade material.Additionally, although sleeve 232 is illustrated as having asubstantially cylindrical or tubular configuration, it should beunderstood that other shapes and configurations of sleeve 232 are alsocontemplated as being within the scope of the present invention.Furthermore, although sleeve 232 has been illustrated and described asbeing formed as a single-piece, unitary structure, it should beunderstood that the distal end portion 232 a could be formed separatelyfrom the remainder of sleeve 232, and coupled together by any knownmethod, such as, for example, by fastening, welding or adhesion.

In one embodiment of instrument 200, the distal-most end portion 270 ofsleeve 232 is secured to the distal end portion 230 a of rod 230 by wayof crimping. In other embodiments, sleeve portion 270 may be connectedto rod portion 230 a by a compression ring similar to compression ring70, or by other connection techniques such as, for example, fastening,welding, adhesion, or other methods of attachment known to those ofskill in the art.

The distal end portion 232 a of sleeve 232 includes at least onerectangular-shaped window or slot 250 extending generally alonglongitudinal axis L, and preferably includes at least a pair of slots250 and 252 (not shown) disposed generally opposite one another so as todefine a pair of longitudinally extending flexible strips of material254, 256. However, it should be understood that the distal end portion232 a of sleeve 232 could define any number of longitudinally extendingslots, including three or more slots, which would in turn define acorresponding number of flexible strips of material disposed between theslots. The slots 250, 252 are provided to facilitate outward buckling ofthe distal end portion 232 a of sleeve 232 upon the imposition ofrelative linear displacement between rod 230 and sleeve 232. Asillustrated in FIG. 8, when reformed toward the expanded configuration,the flexible strips of material 254, 256 will outwardly buckle alongtransverse axis T at a location adjacent the midpoint of slots 250, 252.In the illustrated embodiment of instrument 200, the slots 250, 252 aresubstantially identical in shape and configuration. However, it shouldbe understood that slots 250, 252 may take on different predeterminedshapes and configurations. Additionally, although slots 250, 252 andstrips of material 254, 256 are illustrated as having a generallyrectangular shape, other predetermined shapes and configurations arealso contemplated.

When in the initial configuration (FIG. 7), the distal end portion 232 aof sleeve 232 has a relatively low profile to facilitate positioningadjacent a vertebral body. However, once properly positioned adjacentthe vertebral body, the distal end portion 232 a is mechanicallydeformed by displacing rod 230 relative to sleeve 232. In theillustrated embodiment, such relative displacement is accomplished bylinearly displacing rod 230 relative to sleeve 232 in the direction ofarrow A. In an alternative form of the present invention, the distal endportion 232 a of sleeve 232 may be mechanically deformed toward theexpanded configuration by way of relative rotational displacementbetween rod 230 and sleeve 232.

When reformed toward the expanded configuration (FIG. 8), the distal endportion 232 a of sleeve 232 is outwardly deformed relative tolongitudinal axis L so as to form a number of laterally extendingprojections or protrusions 298 a, 298 b. As discussed above, thedeformed/expanded configuration of instrument 200 may alternativelydefine any number of laterally extending projections, including a singleprojection or three or more projections. Similar to instrument 20,formation of the laterally extending projections and the resultingdisplacement of the vertebral body by instrument 200 isdirectionally-controlled, and can be uniaxial, unidirectional or bothuniaxial and unidirectional. Following displacement of the vertebralbody, the distal end portion 232 a of sleeve 232 may be reformed backtoward its initial insertion configuration by linearly displacing rod230 relative to sleeve 232 in the direction of arrow B. As discussedabove with regard to instrument 20, the distal end portion 232 a ofsleeve 232 may be formed of a shape-memory material, such as, forexample, a shape-memory alloy to aid in reforming distal end portion 232a back toward its initial configuration.

In one embodiment of the invention, at least the distal end portion ofthe elongate member 222 is covered by a flexible membrane 280. Theflexible membrane 280 is preferably formed of a resilient material thatis capable of conforming to the shape of the distal end portion 232 a ofsleeve 232 during reformation between the initial and deformedconfigurations. Such flexible materials include, but are not limited to,silicone, latex, rubber, a polymer or other suitable elastomericmaterials. One purpose of the flexible membrane 280 is to prevent tissueor other foreign material from passing through the slots 250, 252 andbeing deposited within the space between the strips of material 254, 256and the rod 230 and/or between the rod 230 and the remainder of thesleeve 232. As should be appreciated, such a build-up of tissue orforeign material may block or otherwise inhibit reformation of thedistal end portion 232 a of sleeve 232 from the deformed configuration(FIG. 8) back toward the initial configuration (FIG. 7). Although theflexible membrane 280 is illustrated as covering the distal end portionof elongate member 222, it should be understood that the flexiblemembrane 280 could be sized to cover the entire length of the elongatemember 222. It should also be understood that a flexible membranesimilar to flexible membrane 280 may be used in association with thesurgical instrument 20 discussed above and/or the surgical instrument300 discussed below.

Referring now to FIGS. 9-11, shown therein is the distal end portion ofan instrument 300 according to another form of the present invention, asshown in an initial insertion configuration, a partially deformedintermediate configuration, and a fully deformed configuration,respectively. It should be understood that instrument 300 may be used inassociation with applications similar to those discussed above withregard to instrument 20, including both intrabody and interbodyapplications involving displacement of at least a portion of a vertebralbody.

Instrument 300 is comprised of an elongate member 322 extendinggenerally along a longitudinal axis L and having a distal end portion(as shown) and a proximal end portion (not shown) which may be coupledto an actuator mechanism similar to actuator mechanism. The distal endportion is deformable and is configured to outwardly expand upon theimposition of a mechanically induced force. Specifically, the distal endportion is reformable between an initial configuration (FIG. 9) forpositioning adjacent a vertebral body, and a deformed configuration(FIG. 11) for displacement of at least a portion of the vertebral body.Although the illustrated embodiment depicts elongate member 322 ashaving a generally linear, unitary configuration, it should beunderstood that elongate member 322 may take on other configurations aswell, such as, for example, a curvilinear configuration or a hingedconfiguration.

In the illustrated embodiment of instrument 300, the elongate member 322is generally comprised of an inner rod member 330 and an outer sleevemember 332. The inner rod 330 is preferably formed of a substantiallyrigid medical grade material such as, for example, titanium or stainlesssteel. Rod 330 includes a distal end portion 330 a extending from a mainbody portion 330 b. In the illustrated embodiment, the distal endportion 330 a has a rectangular shape and the main body portion 330 bhas a square shape. However, it should be understood that other shapesand configurations of rod 330 are also contemplated as being within thescope of the present invention such as, for example, circular,elliptical or polygonal configurations.

The outer sleeve 332 has a deformable distal end portion 332 a coupledto a main body portion 332 b. The main body portion 332 b has a squareconfiguration defining an inner passage extending therethrough generallyalong longitudinal axis L and sized to slidably receive portion 330 b ofrod 330 therein. How-ever, it should be understood that other shapes andconfigurations of sleeve portion 332 b are also contemplated as beingwithin the scope of the present invention. Preferably, the main bodyportion 332 b is formed of a substantially rigid material, such as, forexample, titanium, stainless steel or other substantially rigid medicalgrade materials.

The deformable distal end portion 332 a of sleeve 332 is at leastpartially formed of a relatively flexible material that is capable ofbeing reformed from the initial configuration illustrated in FIG. 9toward the deformed configuration illustrated in FIG. 1. Preferably,distal end portion 332 b is formed of a relatively elastic material thatis capable of being elastically deformed toward the deformedconfiguration and reformed back toward the initial configuration. Thedeformable distal end portion 332 b may be formed of materialsincluding, but not limited to, titanium, stainless steel, an elastomer,a polymer, a rubber, a composite material or a shape-memory material.Distal end portion 332 b is preferably formed separately from main bodyportion 332 a and connected thereto by any method know to one of skillin the art, such as, for example, by fastening, welding or adhesion.However, is should be understood that distal end portion 332 b couldalternatively be formed integral with main body portion 332 a to definea single-piece, unitary structure.

The deformable distal end portion 332 a of sleeve 332 includes aplurality of wall elements 354-357 that are flexibly interconnected by anumber or interconnection portions 360. In one embodiment of theinvention, the interconnection portions 360 are defined by forming anopening or channel 362 at locations where adjacent wall elements adjointo one another. In one embodiment of the invention the wall elements354-357 are integrally formed to define a unitary, single-piecereformable structure that is collapsible to define a relativelylow-profile insertion configuration and expandable to define anoutwardly deformed configuration.

To aid in reformation of the distal end portion 332 a between theinsertion and deformed configurations, the distal end portion 332 a ofsleeve 332 is preferably flexibly coupled to the main body portion 332b. In one embodiment. the outer wall elements 354, 355 each include aflexible interconnection portion 366 defined by forming an opening orchannel 367 adjacent their respective distal end portions 354 a, 355 a.The distal end portions 354 a, 355 a of the outer wall elements 354, 355are in turn coupled to inner surfaces of the main body portion 332 b ofsleeve 332, such as, for example, by fastening, welding or adhesion. Theouter wall elements 354, 355 are separated by a distance sufficient toreceive the distal end portion 330 a of rod 330 therebetween.

As shown in FIG. 9, the insertion configuration has a substantiallyrectangular-shaped profile, with each of the wall elements 354-357 beingdisposed in a substantially uniform orientation (i.e., parallel to oneanother), and with the two inner wall elements 356, 357 being disposedbetween the two outer wall elements 354, 355. As shown in FIG. 11, thedeformed/expanded configuration has a substantially triangular-shapedprofile, with the two inner wall elements 356, 357 being disposed in asubstantially parallel and co-linear orientation, and the two outer wallelements 354, 355 being disposed at an angle θ relative to inner wallelements 356, 357. In one embodiment, the angle θ is about 30°-45°. Itshould be understood that other insertion and expanded configurationsare also contemplated as falling within the scope of the presentinvention. Additionally, although the reformable distal end portion 332b of sleeve 332 has been illustrated and described as including fourwall elements 354-357, it should be understood that any number of wallelements may be flexibly interconnected to form the reformable distalend portion 332 b.

When in the initial folded configuration illustrated in FIG. 9, thedeformable distal end portion 332 a of sleeve 332 has a relatively lowprofile to facilitate positioning adjacent a vertebral body. However,once properly positioned adjacent the vertebral body, the distal endportion 332 a is mechanically deformed by displacing rod 330 relative tosleeve 332. In the illustrated embodiment, such relative displacement isaccomplished by linearly displacing rod 330 relative to sleeve 332 inthe direction of arrow B, and is initiated by the selective actuation ofan actuator mechanism (not shown).

As shown in FIG. 10, relative displacement of rod 330 in the directionof arrow B causes the distal end portion 330 a of rod 330 to engage theinterconnection portion 360 extending between the inner wall elements356, 357, thereby initiating the outward expansion or unfolding of thewall elements 354-357. In one embodiment of the invention, the distalend portion 330 a of rod 330 is secured to the interconnection portion360, such as, for example, by fastening, welding or adhesion. However,it should be understood that the distal end portion 330 a of rod 330need not necessarily be rigidly secured to interconnection portion 360,but could alternatively form an abutting relationship therewith toinitiate the outward expansion of wall elements 354-357.

As shown in FIG. 11, when reformed to the deformed configuration, thewall elements 354-357 are unfolded and expanded outwardly relative tolongitudinal axis L so as to form laterally extending projections orprotrusions 398 a, 398 b disposed along a transverse axis T. Althoughinstrument 300 has been illustrated and described as including a pair ofoppositely disposed projections 398 a, 398 b when in the expandedconfiguration, it should be understood that the distal end portion 332 aof sleeve 332 may be configured to define any number of projections,including a single projection or three or more projections. Further,similar to instrument 20, the expansion of the distal end portion 332 aof sleeve 332 and the resulting displacement of the spinal structureaccomplished by instrument 300 is directionally-controlled, and can beuniaxial, unidirectional or both uniaxial and unidirectional.

Following displacement of the vertebral body, the distal end portion 332a of sleeve 332 may be reformed toward its initial insertionconfiguration by linearly displacing rod 330 relative to sleeve 332 inthe direction of arrow A (FIG. 11). As discussed above with regard toinstrument 20, the distal end portion 332 a of sleeve 332 may be formedof a shape-memory material, such as, for example, a shape-memory alloy(“SMA”) to aid in reforming distal end portion 332 a back toward itsinitial configuration.

Referring to FIG. 12, shown therein is a lateral view of a spinalcolumn, illustrating the introduction and expansion of instrument 20within a vertebral body V₁ to perform intrabody distraction. The distalend portion 32 a of sleeve 30 is initially passed through an accessopening (not shown) extending through an outer wall of the vertebralbody V₁ while in the undeformed initial configuration illustrated inFIG. 5. Subsequent to insertion within the vertebral body V₁, the distalend portion 32 a of sleeve 32 is reformed by a mechanically-inducedforce created by linearly displacing rod 30 relative to sleeve 32 in thedirection of arrow A. As a result, the distal end portion 32 a isoutwardly deformed to form opposing projections 198 a, 198 b extendingalong transverse axis T. Such outward deformation is particularlyuseful, for example, to compact or compress cancellous bone against theinner cortical wall of the vertebral body V₁ to form a cavity C therein.Compaction of the cancellous bone may have the effect of exerting anoutward force on the inner surface of the cortical wall, making itpossible to elevate or push broken and/or compressed bone back to ornear its original pre-fracture condition or another desired condition.Alternatively, the opposing projections 198 a, 198 b may bear directlyagainst the inner surface of the cortical bone to reduce a compressionfracture in the vertebral body V₁.

In one form of the present invention, access into the inner cancellousregion of the vertebral body V₁ is be accomplished by drilling arelatively small access opening through an outer wall of the vertebralbody, such as, for example, through the pedicular region of thevertebral body V₁. The undeformed initial configuration of the distalend portion 32 a of sleeve 30 is sized to pass through the small accessopening to gain access to the inner cancellous region of the vertebralbody V₁. In this manner, insertion of the distal end portion 32 a ofsleeve 32 is accomplished in a minimally invasive manner. Additionally,unlike certain prior art devices that require a relatively larger accessopening to accommodate spreading of the proximal end portions ofopposing members attached to one another in a scissors-like manner, onlythe distal end portion 32 a of sleeve 32 is outwardly expanded whenreformed toward the deformed configuration.

In one embodiment of the invention, the initial configuration of thedistal end portion 32 a of sleeve 32 is sized to pass through an accessopening having a diameter between about 1 millimeter and about 5millimeters. In a specific embodiment, the initial configuration of thedistal end portion 32 a is sized to pass through an access openinghaving a diameter of about 3 millimeters. In another embodiment of theinvention, the deformed configuration of the distal end portion 32 a ofsleeve 30 is sized to displace the vertebral body V₁ within a range ofabout 3 millimeters to about 15 millimeters. In a specific embodiment,the deformed configuration of the distal end portion 32 a is sized todisplace the vertebral body V₁ about 10 millimeters. In another specificembodiment of the invention, the instrument 20 is capable of assuming adeformed configuration that is over three times greater than its initialconfiguration. Although ranges and specific sizes of the initial anddeformed configurations of distal end potion 32 b of sleeve 32 have beenset forth above, it should be understood that such ranges and specificsizes are exemplary and are not intended to limit the scope of thepresent invention in any manner whatsoever.

Following displacement of the vertebral body V₁, the distal end portion32 a of sleeve 32 is reformed toward its initial insertion configurationby displacing rod 30 relative to sleeve 32 in the direction of arrow B.As a result, the opposing projections 198 a, 198 b are inwardly deformedto the extent necessary to provide uninhibited removal of the distal endportion 32 a of sleeve 32 from the vertebral body V₁. As discussedabove, reformation of the instrument 20 back toward its initialinsertion configuration may be facilitated by forming the distal endportion 32 a of sleeve 32 from a shape-memory material. Following theremoval of instrument 20 from the vertebral body V₁, the cavity C may befilled with a biocompatible filling material, such as, for example,methylmethacrylate cement (e.g., bone cement), a structural implant,and/or a therapeutic substance to promote healing. Once set to ahardened condition, the filling material provides internal structuralsupport to the vertebral body V₁, and more particularly providesstructural support to the cortical bone of the vertebral body V₁.

In another form of the present invention, a cannula assembly 400 may beused to provide minimally invasive access to the vertebral bodies V₁, V₂and/or the disc space D. As shown in FIG. 12, use of the cannulaassembly 400 permits displacement of the vertebral body V₁ via insertionand manipulation of instrument 20 through a single working channel.Further details regarding a cannula assembly suitable for use inassociation with the present invention are disclosed in U.S. patentapplication Ser. No. 09/692,932 to Foley et al., filed on Oct. 20, 2000,the contents of which are incorporated herein by reference.

The cannula assembly 400 includes a cannula 402 having a distal end 402a and defining an inner working channel 404 extending between the distalend 402 a and a proximal end (not shown). The length of the cannula 402is sized such that the proximal end (not shown) of the cannula 402 ispositioned beyond the skin of the patient when the distal end 402 a ispositioned adjacent the vertebral body V₁. One advantageous feature ofthe cannula assembly 400 is the relatively large cross section of theworking channel 404 extending through cannula 402. Such a large crosssection permits the surgeon to introduce a wide variety of instrumentsor tools into the working channel 404, as well as the simultaneousintroduction of two or more instruments or tools. Furthermore, therelatively large cross section of working channel 404 permits a widerange of motion of the instruments and tools.

The cannula assembly 400 may also include an endoscope assembly (notshown) mounted to the proximal end portion of the cannula 402 to provideremote visualization of the surgical site. The endoscope assembly mayinclude, for example, a viewing element 406 disposed within the workingchannel 404 of cannula 402 and having a distal end 406 a positionedadjacent the surgical site. The viewing element 406 is preferablylinearly and rotatably displaceable within the working channel 404 toprovide a wide degree of visualization of the surgical site. Theendoscope assembly may also include an illumination element (not shown),a remote viewing apparatus such as an eyepiece (not shown), and/orirrigation and aspiration components (not shown) extending along viewingelement 406. One embodiment of an endoscope assembly suitable for use inassociation with the present invention is described in U.S. Pat. No.6,152,871 to Foley et al., issued on Nov. 28, 2000, the contents ofwhich are incorporated herein by reference. The cannula assembly 400 mayalso include a microscopic viewing system (not shown) mounted to theproximal end portion of the cannula 402 to provide microscopicvisualization of the surgical site. One embodiment of a microscopicviewing system suitable for use in association with the presentinvention is described in U.S. patent application Ser. No. 09/815,693 toFoley et al., filed on Mar. 23, 2001, the contents of which areincorporated herein by reference.

Although FIG. 12 illustrates the use of instrument 20 to at leastpartially displace the vertebral body V₁, it should be understood thatinstruments 200 and 300 could alternatively be used to perform thetechnique. It should also be understood that in addition to performingintrabody distraction, instruments 20, 200 and 300 may be used toperform interbody distraction of one or both of the adjacent vertebralbodies V₁, V₂, such as, for example, to increase the height of the discspace D. Interbody distraction of adjacent vertebral bodies V₁, V₂ mayalso be effective to increase the distance between correspondingportions of the vertebral bodies V₁, V₂. In cases involving brittleportions of the vertebral bodies V₁, V₂, shims may be positioned betweenthe deformable distal end portion 32 a of sleeve 32 and the vertebralbodies V₁, V₂ to distribute the compressive force over a larger area toavoid puncturing or crushing of the brittle portions. It shouldadditionally be understood that although the distraction techniqueillustrated in FIG. 12 uses a posterior surgical approach, othersurgical approaches are also contemplated, such as, for example,anterior, lateral, and postero-lateral approaches.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiments have been shown and described and thatall changes and modifications that come within the spirit of theinvention are desired to be protected.

1.-79. (canceled)
 80. A method for treatment of the spine, comprising:providing an instrument including a deformable distal portion having aninsertion configuration and a deformed configuration, the deformedconfiguration defining at least one transverse projection arranged alonga single transverse axis; positioning the deformable distal portionadjacent a spinal structure while in the insertion configuration; anddeforming the distal portion toward the deformed configuration touniaxially displace at least a portion of the spinal structure along thetransverse axis.
 81. The method of claim 80, wherein the deforming isdirectionally controlled.
 82. The method of claim 80, furthercomprising: deforming the distal end portion back toward the insertionconfiguration; and removing the distal end portion from the spinalstructure.
 83. The method of claim 80, wherein the positioning comprisesinserting the deformable distal portion through an outer wall of avertebral body; and wherein displacement of the at least a portion ofthe spinal structure comprises compacting cancellous bone to form acavity within the vertebral body.
 84. The method of claim 80, whereinthe positioning comprises inserting the deformable distal portionthrough an outer wall of a vertebral body; and wherein displacement ofthe at least a portion of the spinal structure comprises at leastpartially reducing a compression fracture in the vertebral body.
 85. Themethod of claim 80, wherein the positioning comprises inserting thedeformable distal portion into an intervertebral disc space betweenadjacent vertebral bodies; and wherein displacement of the at least aportion of the spinal structure comprises exerting a force onto theadjacent vertebral bodies and distracting the intervertebral disc space.86. The method of claim 80, wherein the deforming of the distal portiontoward the deformed configuration comprises selectively controlling thedeforming to generate a controlled magnitude of force against the atleast a portion of the spinal structure.
 87. The method of claim 80,wherein the instrument includes a first member and a second memberengaged with the first member, the second member comprising thedeformable distal portion, the deforming of the distal portion occurringin response to relative displacement between the first and secondmembers, the relative displacement between the first and second membersbeing regulated to generate a controlled magnitude of force against theat least a portion of the spinal structure.
 88. A method for treatmentof the spine, comprising: providing an instrument including a firstmember and a second member engaged with the first member, the secondmember including a deformable distal portion having an insertionconfiguration and a deformed configuration; positioning the deformabledistal portion adjacent a spinal structure while in the insertionconfiguration; and deforming the distal portion toward the deformedconfiguration in response to relative displacement between the first andsecond members, the deformed configuration displacing at least a portionof the spinal structure.
 89. The method of claim 88, wherein therelative displacement between the first and second members is regulatedto control the deforming and to generate a controlled magnitude of forceagainst the at least a portion of the spinal structure.
 90. The methodof claim 88, wherein the deforming is directionally controlled.
 91. Themethod of claim 88, wherein the deformed configuration of the distalportion defines at least one transverse projection arranged along asingle transverse axis; and wherein the deforming of the distal portiontoward the deformed configuration uniaxially displaces at least aportion of the spinal structure along the transverse axis.
 92. Themethod of claim 88, further comprising: inserting a cannula having aworking channel through the skin and tissue of a patient; positioning adistal end of the cannula adjacent a vertebral body; and inserting thedistal end portion of the instrument through the working channel toaccess the vertebral body.
 93. The method of claim 92, furthercomprising inserting a viewing element into a working channel of thecannula to provide visualization of the vertebral body.
 94. A method fortreatment of the spine, comprising: providing an instrument including adeformable distal end portion having an insertion configuration and adeformed configuration; inserting a cannula having a working channelthrough the skin and tissue of a patient; positioning a distal end ofthe cannula adjacent a spinal structure; inserting the deformable distalend portion of the instrument through the working channel of thecannula; positioning the deformable distal end portion proximatelyadjacent the spinal structure while in the insertion configuration; anddeforming the deformable distal end portion toward the deformedconfiguration to displace at least a portion of the spinal structure.95. The method of claim 94, wherein the deformed configuration of thedeformable distal end portion defines at least one transverse projectionarranged along a single transverse axis; and wherein the deformingresults in uniaxially displacing the at least a portion of the spinalstructure along the single transverse axis.
 96. The method of claim 94,wherein the deforming is directionally controlled.
 97. The method ofclaim 94, wherein the positioning comprises inserting the deformabledistal end portion through an outer wall of a vertebral body; andwherein displacement of the at least a portion of the spinal structurecomprises compacting cancellous bone to form a cavity within thevertebral body.
 98. The method of claim 97, wherein the compactingresults in at least partially reducing a compression fracture in thevertebral body.
 99. The method of claim 94, wherein the deforming of thedeformable distal end portion toward the deformed configurationcomprises selectively controlling the deforming to generate a controlledmagnitude of force against the at least a portion of the spinalstructure.
 100. The method of claim 94, wherein the instrument includesa first member and a second member engaged with the first member, thesecond member comprising the deformable distal end portion, thedeforming of the distal end portion occurring in response to relativedisplacement between the first and second members.
 101. The method ofclaim 100, wherein the relative displacement comprises linearlydisplacing the first member relative to the second member.
 102. Themethod of claim 100, further comprising mechanically regulating therelative displacement between the first and second members to generate acontrolled magnitude of force against the at least a portion of thespinal structure.